Method and apparatus for the production of discrete agglomerations of particulate matter

Abstract

A method and apparatus is provided for the generation of agglomerations of particulate material in a liquid. Agglomerations are built up at a point under the effect of an electric field and ejected by electrostatic means. The size of the agglomeration is dependent upon the strength of the electric field, point geometry, the nature of the liquid and the nature of the particles. Agglomerations of particles in the range of from 1 to 500 microns are produced The invention is useful for non-impact printing and other applications where delivery of agglomerations of particles is useful such as in inhalable pharmaceuticals.

What is claimed is:  
     
       1. A method for agglomerating particulate matter in a liquid and ejecting discrete agglomerations of said particulate matter in a desired trajectory, comprising the steps of: 
       providing an ejection location;  
       supplying the liquid including the particulate matter to the ejection location;  
       creating an electric field at the ejection location causing said ejection location to become electrically charged, said electric field having a direction generally in a direction of the desired trajectory, said particulate matter experiencing as a result of such electric field a force resulting in agglomeration of the particulate matter and;  
       directly ejecting the agglomerations out of the liquid and away from the ejection location in the direction of the electric field by electrostatic repulsion between the agglomerations and the ejection location.  
     
     
       2. A method according to claim  1 , further comprising the step of pulsing the electric field such that said agglomerations are periodically ejected out of the liquid and away from the ejection location. 
     
     
       3. A method according to claim  1 , further comprising the step of withdrawing excess of said liquid from the ejection location. 
     
     
       4. A method according to claim  1 , further comprising the step of vacuum extracting excess of said liquid from the ejection location. 
     
     
       5. A method according to claim  1 , further comprising providing the ejection location with a needle point having a radius of curvature of 5 to 50 microns. 
     
     
       6. A method according to claim  1 , further comprising providing the ejection location with an elongate edge. 
     
     
       7. A method according to claim  6 , wherein the elongate edge includes a plurality of ejection points. 
     
     
       8. A method according to claim  1 , wherein said agglomerations have a diameter of 1 micron to 500 microns. 
     
     
       9. A method according to claim  1 , wherein the liquid is a non-electrically conducting liquid. 
     
     
       10. A method according to claim  1 , wherein the particulate matter comprises chargeable particles. 
     
     
       11. A method according to claim  10 , wherein the chargeable particles are charged to a polarity which is the same as a polarity of the ejection location. 
     
     
       12. A method according to claim  1 , wherein a size of the agglomerations is dependent upon at least one of a nature of the liquid, the particulate matter and the electric field. 
     
     
       13. A method according to claim  1 , wherein said discrete agglomerations comprise the particulate matter together with a proportion of the liquid. 
     
     
       14. A method according to claim  13 , wherein the proportion of the liquid is dependent upon a nature of the liquid, the particulate matter and the electric field. 
     
     
       15. A method for agglomerating particulate matter in a liquid and ejecting discrete agglomerations of the particulate matter, comprising the steps of: 
       providing an ejection location;  
       supplying the liquid including the particulate matter to the ejection location;  
       creating an electric field at the ejection location, said electric field causing said ejection location to become electrically charged, said electric field having a direction, said particulate matter experiencing as a result of such charge a force resulting in agglomeration of the particulate matter;  
       said electric field acting on the particulate matter such that said discrete agglomerations are directly ejected out of the liquid and away from the ejection location by electrostatic repulsion operating in the direction of the electric field between the agglomerations and the ejection location.  
     
     
       16. A method according to claim  15 , further comprising the step of pulsing the electric field such that said agglomerations are periodically ejected out of the liquid and away from the ejection location. 
     
     
       17. A method according to claim  15 , further comprising the step of withdrawing excess of said liquid from the ejection location. 
     
     
       18. A method according to claim  15 , further comprising the step of vacuum extracting excess of said liquid from the ejection location. 
     
     
       19. A method according to claim  15 , wherein the ejection location is provided by a needle point having a radius of curvature of 5 to 50 microns. 
     
     
       20. A method according to claim  15 , further comprising providing the ejection location with an elongate edge. 
     
     
       21. A method according to claim  20 , wherein the elongate edge includes a plurality of ejection points. 
     
     
       22. A method according to claim  15 , wherein said agglomerations have a diameter of 1 micron to 500 microns. 
     
     
       23. A method according to claim  15 , wherein the liquid is a non-electrically conducting liquid. 
     
     
       24. A method according to claim  15 , wherein the particulate matter comprises chargeable particles. 
     
     
       25. A method according to claim  24 , wherein the chargeable particles are charged to a polarity which is the same as a polarity of the ejection location. 
     
     
       26. A method according to claim  25 , wherein a size of the agglomerations is dependent upon at least one of a nature of the liquid, the particulate matter and the electric field. 
     
     
       27. A method according to claim  15 , wherein said discrete agglomerations comprise the particulate matter together with a proportion of the liquid. 
     
     
       28. A method according to claim  27 , wherein the proportion of the liquid is dependent upon at least one of a nature of the liquid, the particulate matter and the electric field. 
     
     
       29. An apparatus comprising: 
       a body having an ejection location;  
       a liquid supply for supplying a liquid containing a particulate matter to the ejection location; and  
       an electrical supply connected to the body that creates an electric field at the ejection location, said electric field having a direction, said particulate matter experiencing as a result of said electric field a force resulting in agglomeration of the particulate matter to form discrete agglomerations thereof and to eject said discrete agglomerations directly from the liquid supplied at the ejection location in the direction of the electric field.  
     
     
       30. An apparatus according to claim  29 , further comprising a vacuum extraction means for withdrawing excess of said liquid from the ejection location. 
     
     
       31. An apparatus according to claim  29 , wherein the ejection location is a needle point. 
     
     
       32. An apparatus according to claim  29 , wherein the ejection location is an elongate edge. 
     
     
       33. An apparatus according to claim  29 , wherein the ejection location comprises a plurality of points along an elongate edge. 
     
     
       34. An apparatus according to claim  29 , wherein the ejection location comprises a matrix of ejection points. 
     
     
       35. An apparatus according to claim  29 , wherein the ejection location comprises a hemispherical or semi-cylindrical surface having a radius of curvature of 5 to 50 microns. 
     
     
       36. An apparatus according to claim  29 , wherein said electrical supply is pulsed to provide periodic ejection of the agglomerations. 
     
     
       37. An apparatus according to claim  29 , wherein the electrical supply supplies a voltage of 500 to 5000 volts.